According to the semiconservative model, after one round of replication, every new DNA double helix would be a hybrid that consisted of one strand of old DNA bound to one strand of newly synthesized DNA.
A thorough medical evaluation is necessary to determine the cause of a slow heart rate. An electrocardiogram (EKG or ECG), laboratory tests, and other diagnostic studies may be done. Potential medical causes of a slow heart rate include: abnormal heart rhythms.
Sinus bradycardia: A regular but unusually slow heart beat (50 beats/minute or less at rest). Sinus bradycardia can be the result of many things including good physical fitness, medications, and some forms of heart block. Sinus refers to the sinus node, the heart's natural pacemaker which creates the normal regular heartbeat. Bradycardia means that the heart rate is slower than normal. Fainting can occur with sinus bradycardia if the heart slows down even more. This can occur, for example, when the vagus nerve sends a signal to the heart that suddenly drops the heart rate. Choking or gagging can trigger this response which is called the vasovagal reflex.